We have had subzero temps the last two days. Set my thermostat to 72 and gets as high as about 68-69. Used the emergency heat setting and it worked like a charm. Is that normal? Temps have been oddly low winchills up to -27

Pretty much standard for a heat pump. Get ready for $$$ power bills next month.

So there's nothing wrong with it? That's normal for extreme temp?

Christy44- Yes, this is normal. In extremely cold temperatures, the efficiency of a heat pump drops very low and has difficulty extracting heat from the air. Actually, I'm surprised you can reach 68 with such a low outside temperature. A strip heater-note the term "emergency" is 100% efficient but uses a lot of electricity. Read your heater manual, it should tell you how many KIllowatts/hr it will use in these conditions. Multiply that by your per KW cost and you will see how much it will cost per hour. If, for example, your emergency heat is 10KW/hr and your KW cost is 10 cents, it would cost you $1 per hour or $24 per day X 30 days = $720 per month. That's why I said get ready for $$$ next month if you run the emergency heat all the time. Wear a sweater or two and save some money.